Over the last century, an extensive empirical literature has evolved examining the psychosocial adjustment of Children of Alcoholics (i.e., COAs). In general, these investigations have concluded that COAs are at heightened risk for a host of emotional and behavioral problems compared to children of nonalcoholic parents. Conversely, research examining the psychosocial functioning of children whose parents primarily abuse drugs other than alcohol, often referred to as Children of Substance Abusers (i.e., COSAs), is far less evolved than the COA literature. Although results of available studies suggest COSAs are at heightened risk for psychological, social, and behavioral problems, it is far less clear what risk and protective factors may be associated with these observed adjustment problems. To date, the vast majority of investigations of COSAs have focused on children of drug-abusing mothers. Although many leading investigative teams have called for research examining psychosocial adjustment of children with drug-abusing fathers, they have noted consistently efforts to obtain data from such families have been fraught with substantial logistic difficulties. Drug abuse by fathers, with its broad implications for the family environment (e.g., poor parenting, parental conflict, stressful home life) and for the child (e.g., genetic transmission of characteristics that may increase vulnerability), is likely to be an important risk factor for psychosocial maladjustment of their custodial children. Thus, recruitment and methodological barriers notwithstanding, the fact that the effects of paternal drug misuse on their children have been substantially understudied represents a serious gap in the empirical literature. The primary aim of the proposed 5-year study is to examine the psychosocial adjustment of preadolescent custodial children (i.e., 8-12 years of age) who live in two-parent homes with drug-abusing fathers and nonsubstance-abusing mothers (N = 150). To provide a comparative context, these children and their families will be compared to demographically matched children from homes with alcoholic fathers and nonsubstance-abusing mothers (N = 150) and from homes with nonsubstance-abusing parents (N = 150). Additionally, we will be examining several mediating risk factors (e.g., parenting behavior, child temperament, interparental conflict) and protective factors (e.g., children's cognitive ability, social support) that may partially or fully explain differences among the children from homes with either a drug-abusing, alcoholic, and nonsubstance-abusing father. Changes in risk and protective factors, as well as children's adjustment, will be evaluated during the course of three annual waves of data collection.